title: Distinct charge dynamics in battery electrodes revealed by in situ and operando soft X-ray spectroscopy.
abstract: Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensible in studying and the eventual optimization of battery materials. However, soft X-ray spectroscopy, one of the most sensitive probes of electronic states, has been mainly limited to ex situ experiments for battery research. Here we achieve in situ and operando soft X-ray absorption spectroscopy of lithium-ion battery cathodes. Taking advantage of the elemental, chemical and surface sensitivities of soft X-rays, we discover distinct lithium-ion and electron dynamics in Li(Co(¹/₃)Ni(¹/₃)Mn(¹/₃))O₂ and LiFePO₄ cathodes in polymer electrolytes. The contrast between the two systems and the relaxation effect in LiFePO₄ is attributed to a phase transformation mechanism, and the mesoscale morphology and charge conductivity of the electrodes. These discoveries demonstrate feasibility and power of in situ soft X-ray spectroscopy for studying integrated and dynamic effects in batteries.
authors.affiliation: 1] Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China [3].
authors.forename: Xiaosong
authors.initials: X
authors.lastname: Liu
authors.forename: Dongdong
authors.initials: D
authors.lastname: Wang
authors.forename: Gao
authors.initials: G
authors.lastname: Liu
authors.forename: Venkat
authors.initials: V
authors.lastname: Srinivasan
authors.forename: Zhi
authors.initials: Z
authors.lastname: Liu
authors.forename: Zahid
authors.initials: Z
authors.lastname: Hussain
authors.forename: Wanli
authors.initials: W
authors.lastname: Yang